Preparation of hydroxyethyl-2, 5-dichlorobenzene



Patented Sept. 21, 1948 y it 2,449,877

UNITED STATES PATENT OFF-ICE PREPARATION OF HYDROXYETHYL-2,5- DICHLOROBENZENE Thomas S. Carswell, Longmeadow, and Ralph F. Hayes, Springfield, Mass., assignors to MonsantoChemical Company, St. Louis, Mo., a corporation of-Delaware "Application December 2, 1943, Serial N0. 512,632

. u Claims. (01. 260-618) No Drawing.

This invention relates to new organic compounds and amethodfor preparing the same. More particularly,'this invention relates to monohydroxy-ethyl-zfi dichlorobenzenes and to a method for preparing-the same. 1

An object of this' invention is the provision of new organic compounds and a method for preparing the same. A particular object of this invention is to provide organic compounds which are valuable intermediates for the production of polymerizable compounds. A further object of this invention is the provision of a process for obtaining these new intermediate organic compounds.

The foregoing objects are accomplished by the following invention which comprises -mono-hydroxy-ethyl-2,5-dich1orobenzenes and a method for the preparation of the same.

The preferred process for preparing monohyzone are separated by fractional distillation. Alpha-chlor-ethyl-2,5-dichlorobenzene and betachlor-ethyl-2,5 dichlorobenzene are colorless liquids possessing the following physical properties. v

Alpha-chlor Beta-chlor compound compound 7 Density, 4;: 1.336 1. 349 Refractive Index, m .Q l. 5590 l. 5630 Boiling Point (at 3 mm. pressure) droxy-ethyl-2,5-dichlorobenzenes according to 2.0

I. Preparation of monochlor-ethyl-2,5-dichlorobenzene 100 parts of ethyl-2,5-dichlorobenzene and about 0.5 part of phosphorous trichloride are placed in a reaction vessel equipped with a stirrer and maintained at a temperature of 5-l5 C. Chlorine gas is then continuously passed into the ethyl-2,5-dichlorobenzene for about 8 hours while subjecting the mixture to rays from a suitable light source, for example, a Mazda lamp or a General Electric Type S-l sunlamp. Hydrogen chloride evolved as a result of the reaction is allowed to escape. From the resulting product, '72 parts of alpha-chlor-ethyl-2,5-dichlorobenzene and 12 parts of beta-chlor-ethyl-2,5-dichloroben- These new chemical'compounds are described and claimed in our co-pending applicationSerial No. 512,633, filed simultaneously herewith.

The phosphorous trichloride catalyst in the above example may be replaced by phosphorous pentachloride or may be omitted entirely, al-

. though when no' catalyst is employed a longer reaction time is required. The amount of phosphorous trichioride or other catalyst may be substantially varied. When desired, the reaction may be carried out at temperatures outside the range given in the above example.

II. Preparation of mono-hydroazy-ethyl-2,5-dichlorobenzene parts of alpha-chlor-ethyl-2,5-dichlorobenzene are mixed with 25 parts of sodium hydroxide and 250 parts of methanol in a reaction vessel equipped with a stirrer. The resulting mixture is boiled under reflux conditions for 8 hours. Thereafter the reaction product is neutralized with hydrochloric acid and freed from sodium chloride by filtration. From the filtrate, 83 parts of alphahydroxy-ethyl-2,5-dichlorobenzene are obtained by fractional distillation. This new chemical compound is a colorless liquid having the following physical properties:

Density, (1;: 1.217 Refractive Index, m k 1.5300 Boiling Point 102 C. at 12 mm. pressure,

71 0. at 2.5 mm. pressure In place of sodium hydroxide, other hydrolyzing agents may be employed, for example, potassium hydroxide. In place of methanol, other mutual solvents for the reactants may be employed, for

example, other lower aliphatic alcohols such as ethanol and propanol.

In a similar manner to that given above, betahydroxy-ethyl-2,5-dich1orobenzene may be prepared from beta-chloro-ethyl-2,5-dichlorobenzene or mixtures of alphaand beta-hydroxy-ethyl- 2,5-dichlorobenzene may be prepared from mixtures of the corresponding chlorine derivatives.

Mono-hydroxy-ethyl-2,5-dichlorobenzenes are valuable as intermediates for the synethesis of new organic compounds, for example, they may be dehydrated to form 2,5-dichlorostyrene or they may be esterified to provide esters of ethyl-2,5- dichlorobenzene or the hydroxy-ethyl group may be oxidized to obtain a keto-2;5-dichlorobenzene. The preparation of 2,5-dichlorostyrene is described and claimed in our co-pending application Serial No. 512,634 filedsimultaneously herewith. I

What is claimed is:

1. A process for preparing alpha-hydroxyethy1-2,5-dichlorobenzene which comprises reacting alpha-chlor-ethyl-2,5-dichlorobenzene with caustic alkali while dissolved inalower aliphatic alcohol.

'2. A process for preparing alpha-.hydroxyethyl-2,5edichlorobenzene which comprises heating a lower aliphatic alcohol solutioncontaining alpha-chlor-ethyl-2,5-dichlorobenzene and 1 caustic alkali.

3. A process for preparing alpha-hydroxyethyl-2,5-dichlorobenzene which comprises forming alpha-chlor-ethyl-2,5-dichlorobenzene by chlorinating ethyl-2,5-dichlorobenzene in-the'side chain and then heating the alpha-chlor-ethylrv 2,5-dichl'orobenzene in the presence of caustic alkali while dissolved in a lower aliphatic alcohol.

4. A :process for preparing alpha-hydroxyethyl-2,5-dichlorobenzene which comprises heating a methanol solution of a1pha-chlor-ethyl-2,5- dichlorobenzene in the presenceofan excess of caustic alkali on a molar basis.

' 5. A process for preparinga mono-hydroxyethyl-2,5-dichlorobenzene which comprises reacting a mono-chloro-ethyl-2,5-dichlorbenzene .with caustic alkali while dissolved in a solution comprising a lower aliphatic alcohol and wat a temperature not exceeding the boiling point of the solution.

6. A process as defined in claim 5, in which the alcohol is methanol.

7. A process for preparing alpha-hydroxyethyl-2,5-dichlorobenzene which comprises heating a methanol solution of alpha-chlor-ethy1-2,5- dichlorobenzene and caustic alkali.

8. A process as defined in claim 5, which includes the additional steps of neutralizing the reaction product, freeing the neutralized mixture fromsalts .loy filtration and then recovering the 1 hydroxy-"ethyl 2,5-dicltlorobenzene by "fractional distillation.

9. A process for preparing a mono-hydroxyethyl-2,5-dichlorobenzene which comprises heating a methanol solution containing a monochlor-ethyl-2,5-dichlorobenzene and caustic alkalLneutralizing the reaction product with a mineral acid; --separating the resulting salt by I flltrationand-then recovering the mono-hydroxys..ethyl.2';5-dichlorobenzene by fractional distillation.

'10. A process "for preparing alpha-hydroxyethyl2,5-dichlorobenzene which comprises heat- .ringiamethanol solution containing alpha-chlorethyl-2,5-dichlorobenzene and caustic alkali, neutralizing .the reaction product with hydrochloric acid separating the resulting-salt by filtration and recovering the a1pha-hydroxy-ethyl-2,5-dichlordbenzene by fractionaldistillation.

S. ---CARSWELL. RALPH F. HAYES.

REFERENCES CITED The following references are of record'in'the file or this-(patent:

.UNITED STATES PATENTS OTHER REFERENCES :Beilstein; ffHandbuchlderOrganisidenChemia" 'Erganzungswerkpvol;*VI, page 236. 

